Exploring, drilling and completing hydrocarbon and other wells are generally complicated, time consuming and ultimately very expensive endeavors. As such, tremendous emphasis is often placed on well access in the hydrocarbon recovery industry. That is, access to a well at an oilfield for monitoring its condition and maintaining its proper health is of great importance in the industry. As described below, such access to the well is generally provided by a well access line accommodated by a drum positioned at the oilfield.
During monitoring and maintaining of a well, a host of oilfield equipment may be located at the oilfield near the well. As indicated, one such piece of equipment may be a drum assembly accommodating a well access line. The well access line itself may be a coiled tubing line capable of delivering a fluid therethrough and to the well. Alternatively, the line may be a wireline configured to deliver a well tool downhole into the well. In the case of coiled tubing, the line may be threaded through an injector arm and into the well, whereas a more conventional wireline may be dropped into the well from a mast over the well. Regardless, several thousand feet of well access line may be accommodated at the drum for delivery into the well, thereby providing well access for a variety of well monitoring and maintenance procedures.
In the case of wireline procedures, several thousand feet of wireline cable may be provided to the oilfield wrapped about the drum assembly. In many cases wireline access to the well proceeds with a logging tool coupled to the wireline and dropped into the well. With the tool positioned downhole, the cable is then pulled uphole by the drum assembly as the logging application proceeds, recording information relative to the well and surrounding formation. In this manner a log revealing an overall profile of the well may be established, with measurements being recorded continuously as a function of depth in the well.
Similarly, a coiled tubing application may proceed with several thousand feet of coiled tubing provided to the oilfield by way of a drum assembly. The coiled tubing may be threaded through a gooseneck arm and injector for driving of the coiled tubing into the well in order to perform an operation within the well. For example, the coiled tubing may be employed in a clean out operation. That is, the coiled tubing may be equipped with a spray tool and directed to an area of accumulated debris within the well. In this manner a fluid may be pumped through the coiled tubing in order to clean out the debris within the well. The coiled tubing may then be pulled uphole and out of the well for subsequent well operations.
Regardless of the particular type of well access line or procedure, such as those noted above, the drum assembly is subjected to a significant amount of strain and tension from the load placed thereon by the line. For example, the withdrawal alone of the well access line from the well places a significant amount of stress on the drum. That is, tension is exerted on the drum during this pulling as a result of the weight of the line and any tools disposed thereon. Additional tension is also exerted on the drum as a result of the friction of the line and the tool being dragged up against the well wall. Furthermore, there may be a significant amount of fluid resistance to the tool being removed, especially at any high rate of speed. The cumulative effects of such tension may lead to plastifying of the drum in particular locations, eventually leaving the drum ineffective for proper use in well access operations. The drum is particularly susceptible to plastifying of this nature at a junction of its core, about which the line is wrapped, and the wall-like flanges at the sides of the core which help to retain the line in position about the core. Unfortunately, once rendered ineffective in this manner, the drum may be replaced at a cost that may be in excess of $80,000 or more.
Furthermore, the frequency of drum replacement for well access operations has risen sharply in the last several years and is likely to continue rising. This is a result of the types of wells which are becoming more and more common. That is, in today's hydrocarbon recovery industry, highly deviated and tortuous wells are becoming more and more common along with deeper and deeper wells. As a result, the tension of the line on the drum is increased due to the added amount of friction and fluid resistance that accompany such wells as well as the added weight of the longer line, perhaps 30,000 feet or longer. Indeed, the life expectancy of a conventional drum regularly employed in such high tension operations is significantly reduced and to date, no significant drum assembly modifications have been implemented to materially alter this fact.